Throughout his career in public life, Ken Livingstone has had an obsession. He has been careful - extremely careful - only ever to refer to that obsession as "Israel". The mask has now slipped and Mr Livingstone's attitude not to Israel but, rather, to Jews has been made plain. Last week we reported a secret meeting that had taken place between a group of Jewish Labour supporters and Mr Livingstone. The intention on their part was to build bridges with a man who could be London's next mayor. To say that the meeting did not go as they had hoped is an understatement. So appalled by Mr Livingstone's words were some of those present that they wrote to the Labour leader, Ed Miliband, to raise their concerns. According to the letter's authors, Mr Livingstone suggested that "as the Jewish community is rich, we simply wouldn't vote for him." The idea that Jews are rich is as classic an antisemitic canard as exists.

He also, the letter writers told Mr Miliband, "used the words Zionist, Jewish and Israeli, interchangeably, as if they meant the same, and did so in a pejorative manner." The correspondents are unimpeachable and loyal to Labour - Rabbi Danny Rich, for instance, and Neil Nerva of the Jewish Labour Movement. As they themselves say, in 2008 they managed to swallow their doubts and vote for him. This time round, however - even if they had been able to ignore his behaviour as Mayor in cosying up to Islamists and welcoming Sheikh Yusuf al-Qaradawi - they will surely find it impossible to vote to put Mr Livingstone in City Hall again. In the end, this is Labour's own responsibility. Even if it is only now that he has been caught using such language, the measure of Mr Livingstone has long been known. In effect, Labour disenfranchised many of its supporters when it chose Mr Livingstone as the party's candidate. Now it will have to live with the consequences of that decision.